In general, an ammunition includes a case having an opening portion formed at a front end thereof and a propellant chamber filled with a propellant therein, a bullet inserted in the opening portion of the case, and a primer installed in a rear base of the case.
In such an ammunition, when an impact acts on a primer in the rear case due to a percussion lock, the propellant within the case is exploded by the impact. At this moment, the bullet is propelled forward at high velocity by the explosive power of the propellant, and the propelled bullet flies forward to reach a target point.
Since a conventional ammunition is configured to have a planar rear portion of the bullet in order to receive the explosive power of the propellant as much as possible, eddy flow of air is generated at the planar rear portion of the bullet during flight, thereby increasing the air resistance against the bullet. As a result, the flying speed of the bullet is decreased, and the shooting range thereof is shortened. Further, a hit ratio is decreased due to increasing of an error between an aiming point and an impact point by lowering the linearity of bullet.
In order to improve the above-described problems, the present applicant has proposed an ammunition in Korean Patent Registration No. 10-0843573. The proposed ammunition includes a streamlined tail portion so as to minimize the air resistance against the rear portion of the bullet, and a wad separately coupled to the streamlined tail portion of the bullet to apply a thrust force to the bullet when the propellant is exploded.
According to the ammunition with such a configuration, the wad provides a thrust force to the bullet by a pressure due to an explosion of the propellant within the propellant chamber to push out the bullet therefrom, and is separated from the bullet when the bullet exits the muzzle. Therefore, only the bullet is propelled forward with a high thrust force. In this case, the streamlined tail portion of the bullet minimizes the frictional resistance with ambient air during flight and prevents the eddy flow at the rear portion of the bullet, so that flight velocity and straightness are improved to lengthen the shooting range and reduce the error between the aiming point and impact point so as to improve the hit ratio.
However, the coupling structure of the wad installed on the streamlined tail portion of the bullet is of an inclined structure gradually expanding in the thrust force acting direction of the wad, and the bullet is made of a soft material such as copper alloy, whereas the wad is made of a hard material such as iron or stainless steel that are harder than the copper alloy. Therefore, a press fitting phenomenon, in which the wad is pushed in and fitted tightly as the streamlined tail portion of the soft bullet is compressed when the strong thrust force of the wad by the explosion pressure of propellant is acting, occurs frequently. If such a press fitting phenomenon occurs, the wad won't be separated properly from the bullet when the bullet exits the muzzle, so that the firing performance is lowered.